This is a flush insert adaptor for the Magpul Type 1 QD socket: https://magpul.com/sling-mount-kit-type-1.html?mp_global_color=118

This design should work for any hollow core stock, if you have access to the inside. For reference, I am currently using it on a MDT Field stock. It uses one of the supplied 10-32 screws from the Magpul set, and is threaded ¾-10, so you can either print the nut supplied, or use a regular steel nut and washer. A ¾" drill is required - I found a forstner bit gave a very clean edge. Make sure you have enough clearance for the nut. 

I printed face down on the Bambu textured build plate, which gave it a very similar exterior finish as my stock. I am currently using ABS, 100% infill. I have not yet done extensive strength testing, but it holds the weight of the rifle with no noticeable flex.